The invention relates to xerographic process control, and more particularly, to the adjustment of photoreceptor voltages based upon photoreceptor segments to account for the non-uniformity of portions of a photoreceptor within a machine.
Xerographic control is well known in the prior art. The art is replete with various sensors and systems for charging control, for exposure and illumination control, for developer control, and for measuring toner concentration and adjusting toner dispensers. For example, U.S. Pat. No. 4,348,099 discloses the uses of test patches, an infrared densitometer, and an electrometer for charge, illumination, toner dispenser, and developer bias control.
One difficulty has been the inability to account for significant electrostatic distinctions between photoreceptor surfaces on different machines, in particular, to account for significant electrostatic distinctions between different segments of the same photoreceptor surface on a given machine. Another difficulty has been the inability to account for the effect of photoreceptor usage and machine down time on different photoreceptor segments. It would be desirable, therefore, to provide more reliable photoreceptor voltage control to produce higher quality copies over the life of the photoreceptor, in particular, to account for the different effects of photoreceptor deterioration on distinct segments of the photoreceptor within a machine.
It is an object, therefore, of the present invention to provide new and improved photoreceptor voltage control by periodically determining photoreceptor characteristics based upon photoreceptor segments for adjusting photoreceptor voltage levels as well as accounting for the effect of photoreceptor usage and machine down time in adjusting distinct photoreceptor segment voltage levels. Other objects and advantages of the present invention will become apparent as the following description proceeds, and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.